Yeast is a widely used organism for production of desired proteins or polypeptides. Expression of foreign proteins or polypeptides in yeast is disclosed in e.g. EP 163,529, U.S. Pat. No. 4,870,008 and U.S. Pat. No. 5,618,676.
For commercial application high yields of the expressed polypeptides is important. A number of different factors will have an impact on the expression yield including the promoter and so-called upstream activating sequences. It is generally accepted that the best result is achieved when a promoter that is homologous to the host organism is used for expression of both native and foreign genes in transformed host cells. Thus for expression of foreign genes in yeast a promoter associated with a yeast gene would be preferred. Several promoters useful for expression of heterologous proteins in yeast are known. The most commonly used yeast promoters include the PGK, TPI, ADH2, PHO5, MFα1 and GAP promoters.
There is, however, a constant need for further promoters that have improved efficiency and the capability of being regulated for use in large scale thus enabling a high level of expression yield in commercial production.